Retrieves the innerHTML from an element located by CSS or XPath and returns it to test.
Resumes test execution, so **should be used inside async function with `await`** operator.
If more than one element is found - HTML of first element is returned.

```js
let postHTML = await I.grabHTMLFrom('#post');
```

@param {CodeceptJS.LocatorOrString} element located by CSS|XPath|strict locator.
@returns {Promise<string>} HTML code for an element
